Key points from article :
HAVOC is NASA's High-Altitude Venus Operational Concept.
Would enable long-term atmospheric habitation and colonization of Venus.
Venus is the closest planet to Earth - with nearly identical size and mass.
Surface temperatures above 400 C and nearly 100x atmospheric pressure.
But 30 miles up, above the acidic clouds, conditions are more tolerable.
Heliem filled airship could unfurl to 3x size of a Boeing 747.